Segmental ring wheel



July 17, 1928.

T. L-ARSSON SEGMENTAL RING- WHEEL Filed Aug. 22, 1924 Patented July 17, 1928.

UNITED STATES- 1,677,866 PATENT OFFICE.

THURE LARSSON, OF WORCESTER, MASSACHUSETTS, ASSIGNOR T NORTON COMPANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

SEGMENTAL RING WHEEL.

Application filed August 22, 1924. Serial No. 783,681.

My invention relates to grinding wheels and more particularl to a wheel of the ring or cylinder type, w ich is used for plane surface grinding.

It has been customary for wheels used in plane surface grinding to be made in a ring shape and suitablyfastened to a metal chuck as y means of sulphur or other suitable cementing material. Such rings are expensive to make and are frequently broken during the process of manufacture as well as during use.

. It is an object of my invention to overcome this difficulty by using segments of an abrasive ring instead of a unitary ring itself and to rovide a mechanical fastening device toho (1 such segments in place on a driving head in various positions of adjustment according to the degree of wear which has taken place.

Heretofore, it

to shape abrasive segments with a convex innerand a concave outer surface of such a curvature as to engage. a corresponding surface of a. chuck or holder. Difficulties have been experienced in accurately shaping the abrasive segments to conform to the surface of the chuck, due partially to warp age in the moulding and firing operations.

Unless the contacting face of the abrasive segment accurately fits the surface of the chuck, there is great danger of the segment cracking, due to internal strains set up within the segment as it is clamped in position in the chuck. To overcome this, it has been proposed to provide the segment with lands which engage the chuck only in limited spaced areas. m

' It is a further object of my invention to provide a. chuck of a simplified construction that will adjustably and securely support segments having lands on their supportin faces and thus minimize the breakage an increase the efliciency of this type of grinding wheel.

With this and other objects in view as will be apparent to one skilled in the art, my invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawings in which like reference numerals indicate like parts:

Fig. 1 is a sectional view of" a drivin ring having abrasive segments mounte J thereon;

the segments are has been common practice thereof.

Fig. 2 is a sectional view showing how located when newly mounted;

Fig. 3 is a similar view showing the segments half worn down;

Fig. 4 likewise shows the segments in their final positions; and Fig. 5 is an isometric detail showing one of the clamping blocks.

In accordance with my invention I pro pose to employ abrasive segments suitably shaped for mounting on a driving head and held in place against the outer periphery of a metal ring by clamping blocks arranged between adjacent segments. Referring to the drawings, I have illustrated a portion of the metal ring 10 adapted to be fastended on a driving head so as to rotate about the axis of the ring. The outer surface 11 of the rm is substantially cylindrical in shape an is adapted to have the abrasive segments clamped thereagainst. A shoulder 12 on the ring serves to hold an annular flange 13 and prevent upward movement A setof abrading segments 15, made of suitable abrasive material, such as ceramicbonded crystalline alumina or silicon carbide, are disposed around the ring 12 against the surface 11 and held in place by clamping blocks 16, 17 and 18. The clamping blocks, one of which is illustrated in Fig. 5, are fastened to the ring 10 by means of screws 20 whose heads are preferably countersunk in the clamping blocks. The segments 15 are separated longitudinally a suitable distance and the screws 20 passed therebetween, so that each block engages the ends of adjacent abrasive segments.

While various types and shapes of abrasive segments may be employed within the scope of my invention, I prefer to form opposed lands or projections 21 and 22 near the ends of the abrasive segments so that the clamping blocks may be sure of having the pressure applied thereby transmitted directl through the abrasive block in a straight line to the ring 10. If a segment were thicker in the center than at the end, this clamping pressure would tend to crack the segment. If it is desired to fill the space 23 between the central portion of the segment and the ring, this may be done by the use of felt or t e like which will prevent the admission of dirt to this part ly and easily manufactured and quickly as-' and also assist in receiving and transmitting some of the presure applied to the segments.

It will be noted by inspection of Figures 2, 3 and 4 that the clamping screws which hold the upper two blocks 16 and 17 in place are surrounded by sleeves 25. which are somewhat shorter than the thickness of the abrasive segment. Also, as shown in Fig. 5, the clampmg block may have an 1nner facing 26 of soft metal, such as lead, which will contact with and clamp against the abrasive block, and so make less liable anyfracturing of the same due to excessive pressure.

lVhen the abrasive segments 15 are of full sizethey are fitted onto the ring with their upper portions in contact with the annular flange 13 and the clamping blocks engage only the outer peripheries of the segments. When the segments 15 are worn down nearly to the under surface of the ring, an adjustment is made, as shown in Fig. 3, to hold them in a more exposed position. end, the blocks 17 and 18 are released from contact with the segments and the latter are moved out until the block 16 can be moved inwardly until it contacts with the sleeve 25. The abrasivesegments are then clamped in 'place with their upper faces 27 engaging the under sides of the blocks 16. which will prevent them from moving upwardly under the pressure of grinding. The sleeve 25 limits the inward movement of the clamping block to a correct position. In this case the two lower blocks 17 and 18 clamp the abrasive segment against the ring 10. In

the position shown in Fig. 4, the second block 17 has also been moved inwardly into contact with the sleeve and only the lower clamping block 18 engages the segment.

It will now be apparent that I have provided a simple manner of fastening abrasive segments to a chuck and that segments may be readily'substituted for the unitary abrasive rings heretofore used in plane surface grinding. This construction may be cheap- To this its periphery with their outer ends projecting beyond the'ring to form a plane grinding surface and a set of clamping blocks ends of each pair of segments and hold the segments against the supporting ring and means for fastening one or more of said a clamping blocks in position above the abrasive segment to form a member arranged to receive the thrust of the grinding operation, the remainder of the clamping blocks engaging the periphery of the segment to hold it againstthe supporting ring.

3. A grinding wheel comprising a supporting ring, a plurality of abrasive segments arranged in contact with the outer periphery of said ring, a set of clamping blocks arranged to clamp to the ring the adjacent ends of each pair of segments. and means to fasten said blocks to the supporting ring, said clamping blocks andv their fastening means being constructed and arranged so that all of the blocks may be clamped against the peripheries of the segments or so that one or more of each set of clamping blocks may be moved inwardly toward the ring to serve as a thrust support for the segment.

4. A driving head for a grinding wheel comprising a supporting ring having an outer cylindrical surface against which a row of abrasive segments may be adjustably clamped, sets of clamping blocks spaced to be located between the segments, and means for adjustably mounting the blocks on the ring, said parts being so constructed and arranged that a set of blocks between adjacentsegm'ents may clamp against the outer surfaces thereof and hold the segments in frictional engagement with the ring and certain of the blocks of the set are movable to engage the inner ends of the segments in different adjusted positions.

Signed at Worcester, Massachusetts, this 21st day of August, 1924.

THURE LARSSON. 

